The use of peroxy acid bleach precursors in water releasable combination with a non particulate sheet substrate is known in the art, being disclosed in British Pat. Nos. 1,586,769 and 2040983.
Numerous classes of peroxybleach precursors have also been disclosed in which the leaving group contains a radical conferring water solubility. One such class is the acyl oxybenzene sulphonates which are disclosed in British Pat. Nos. 864,798 and 836,988.
However it has now been found that aliphatic peroxy acids having a range of bleach performance previously thought to be unobtainable under domestic laundry washing conditions can be produced in the wash solution by the reaction of certain types of peroxyacid precursors with alkaline hydrogen peroxide. This range of bleaching performance encompasses the bleaching of fugitive dyes in the wash solution, the removal of conventional bleach sensitive stains such as tea, wine and coffee on fabric and also the removal of accumulated soil stains resulting from incomplete previous washes, the so called `dingy fabric clean up`. The chemical instability of precursors, in powdered detergent compositions, particularly where the precursors have appreciable water-solubility, is well known and is acknowledged in BP No. 864,798 and is sought to be overcome therein by employing a coarse particle size for the precursor material. However, where the precursor molecule is inherently of lower solubility e.g. by virtue of the size of the acyl group and/or the size and nature of the leaving group, the use of a coarse particle size has a markedly adverse effect on the rate of precursor solubility in the wash solution. On the other hand, the incorporation of the acyl oxybenzene sulphonate into a non-particulate substrate permits the use of the precursor in very finely divided form without an accompanying loss in stability and also assists in improving the rate of peroxyacid generation from the accordingly one object of the present invention is the formulation of a detergent additive product in a non particulate form incorporating a precursor of an aliphatic organic peroxy acid of defined carbon chain length. Another object of the invention is the formulation of a non particulate detergent additive product providing enhanced `dingy fabric` clean up when used in a detergent liquor containing a source of alkaline hydrogen peroxide. precursor in a wash liquor.